Various camera-based surveillance systems are well known and used in a variety of applications for security purposes. At the base level these include fixed cameras that have a pre-set field of view. The field of view of these cameras can be extended by introducing a pan facility so that the camera scans across a given field of view at a predetermined rate. More sophisticated surveillance systems have cameras that can be remotely controlled to adjust pan, tilt and zoom. Typically these cameras are part of a monitored network.
In a monitored network a surveillance operator sits at a central console and continuously views monitors displaying images from each camera in the network. When a suspicious activity is sighted the operator controls the camera to pan, tilt and zoom to obtain the best available view of the suspicious activity. In large networks of cameras the effectiveness of surveillance can be limited by the skill and capacity of the operator.
Whether standalone or part of a network, the cameras have a limited field of view. It is impossible for an operator to detect and react to activity outside of the field of view of the camera. Even if the camera is set to scan there will still be times when surveillance areas are not visible to an operator. The only way to provide total surveillance is to have an extensive network of cameras with carefully interlocked fields of view. This places an even greater load on the operator charged with monitoring the cameras.
In our international application, PCT/AU2006/000113, we describe a controller incorporating two joysticks to assist operators to control multiple cameras. Notwithstanding the significant improvement available with the use of our innovative controller, surveillance capacity is still often limited by the operator.
Large surveillance tasks usually require a large number of cameras to provide extensive coverage. A large number of cameras places a load on the operator, as mentioned above, but also involves a significant installation cost. We have previously described a track mounted camera for a surveillance system that reduces the number of cameras required to achieve broad surveillance. This is described in our earlier applications, for example Australian patent number 762221 for “A Surveillance System”. Nonetheless, the problem of monitoring and controlling multiple track mounted cameras may still become intractable.
Even with the improvements we have provided it is still difficult for an operator to maintain constant surveillance of a large area, yet in many locations such as grocery stores and gaming establishments, this is exactly what is required. The only solution available is to employ additional staff and to break the surveillance area into zones. This approach is costly in wages and causes handover difficulties if zones are adjacent.